Best thing to do is contact me via the school website or Facebook page, then I can send you the details from there. I don't want to use my private profile for work 🙏. Thanks.
For non-formal schools, the parent must obtain an ED visa first, then the children can apply for a Non-O at a Thai consulate/embassy outside of Thailand, then enter Thailand on that visa.
For formal schools (University), they should be able to process the visa for the kids in-country, but best to check with them first though.